The invention concerns a process for the rotary truing of boards and similar elongated wood products by means of a plurality of adjustably supported guide bodies, which together form a flat board guide channel extending along the longitudinal axis of the frame and having a twist around the longitudinal axis of the frame, said twist being variable by the adjustment of the guide bodies.
Boards and similar plate like elongated wood products may be cut by chipless cutting methods from the sides of flattened logs or tree trunks. These boards or similar wood products have not only curvatures, but also twists, i.e. they are turned or twisted around their longitudinal axis. In numerous applications, this deformation prevents any automatic further processing of the boards. The intensity of the twist increases with the inclination at which the blades cutting the board are set against the longitudinal direction of the wood.
By means of a known apparatus of the aforementioned type (for example, Gonner et al U.S. Pat. No. 4,977,940) the boards may be subjected to a rotary straightening process, so that they lose their twist due to the manufacturing process and become suitable for further processing.
In the case of this known apparatus in a plurality of successive guide stands, rollers are provided as the board guide bodies. The guide stands are pivoted around a common axis, for example the longitudinal axis of the frame, in a manner such that together they form a board guide channel, the twist around the longitudinally axis whereof is chosen so that it straightens the existing twist of the boards.
As the twist of the boards varies depending on the manufacturing conditions, the type of wood and its properties, the guide stands of the known apparatus are individually equipped with separate pivot drives to move them into the pivoting position required. The control of these individual pivot drives is relatively expensive. In addition, the necessary design effort is relatively high.
In a known apparatus for example, Hobbs U.S. Pat. No. 2,399,348 for the bending of laminated work pieces to be glued together, a plurality of parallel bending stops may be moved against the work piece in order to press it against a group of stationary stops. However, the work piece is not twisted in the process, but bent. Furthermore, the work piece does not travel in a guide channel, but is inserted between the two groups of bending stops prior to their displacement.
It is therefore the object of the present invention to develop an apparatus of the aforementioned generic type so that it is very sturdy while having a simple design configuration; said apparatus making possible the adjustment of the board guide channel.